(本题满分 11 分) 已知矩阵 $A = \begin{pmatrix} 0 & -1 & 1 \\ 2 & -3 & 0 \\ 0 & 0 & 0 \end{pmatrix}$ . (I)求 $A^{99}$ （Ⅱ）设3阶矩阵 $\pmb {B} = (\pmb {\alpha}_1,\pmb {\alpha}_2,\pmb {\alpha}_3)$ 满足 $B^{2} = BA$ 记 $B^{100} = (\beta_{1},\beta_{2},\beta_{3})$ ，将 $\beta_{1},\beta_{2},\beta_{3}$ 分别表示为 $\alpha_{1},\alpha_{2},\alpha_{3}$ 的线性组合.